Preparation of a Well-Defined Silica-Supported Nickel-Diimine Alkyl Complex − Application for the Gas-Phase Polymerization of Ethylene

Abstract

The interaction of [(α-diimine)Ni(CH2SiMe3)2] (1) (α-diimine = 2,3-dimethyl-1,4-[(2′,6′)-diisopropylphenyl]-N,N′-diazadiene) with the silanol ≡Si−OH groups of Aerosil SiO2-(700) leads to the formation of the surface complex [≡SiO−Ni(α-diimine)(CH2SiMe3)] (2) with the concomitant emission of 1 mol equiv of SiMe4 (TMS). The surface complex characterized by IR, chemical and mass balance analyses, solid-state NMR, and EXAFS has been activated by gaseous BF3 to give an active gas-phase ethylene polymerization catalyst. The polymers thus obtained present a highly branched structure. The activity is attributed to the formation of the putative surface ion pair [≡SiOBF3]−[Ni(α-diimine)(CH2SiMe3)]+.